Internal combustion engines are supplied with a mixture of air and fuel for combustion within the engine that generates mechanical power. To maximize the power generated by this combustion process, the engine is often equipped with a turbocharged air induction system. A turbocharged air induction system includes a turbocharger that uses exhaust from the engine to compress air flowing into the engine, thereby forcing the air into a combustion chamber of the engine than the engine could otherwise draw into the combustion chamber. This increased supply of air allows for increased fueling, resulting in an increased engine power output.
A turbocharger generally comprises a compressor wheel mounted on one end of a single shaft in a compressor housing and a turbine wheel mounted on the other end of the shaft in a turbine housing. Typically, the turbine housing is formed separately from the compressor housing. A bearing housing is connected between the turbine and compressor housings for containing bearings for the shaft. The turbine housing receives exhaust gas from the engine and directs it to the turbine wheel which is driven by the exhaust gas. The turbine assembly thus extracts power from the exhaust gas and drives the compressor.
The turbine wheel is typically made of a very dense material and rotates at very high speeds during operating of the turbocharger. In order to limit the damage to the turbocharger and engine, measures are generally taken to try to contain the fragments of the turbine wheel in the event that the turbine wheel fails during operation of the turbocharger. One such measure is thick walled, heavy housings surrounding the turbine wheel. However, such housings are relatively expensive and can add significant weight to the turbocharger.